:root {
  --color-surface: #f9f9f9;
  --color-surface-alt: #f0f0f1;
  --color-surface-deep: #e4e4e5;
  --color-ink: #464953;
  --color-ink-soft: #6b6e7b;
  --color-ink-muted: #787b87;
  --color-line: #d9d9db;
  --color-primary: #3356cc;
  --color-primary-ink: #ffffff;
  --color-primary-soft: #dde2f3;
  --color-accent: #6a14eb;
  --color-accent-ink: #ffffff;
  --color-highlight: #dfd0f6;
  --color-focus: #6807f8;
  --color-contrast-surface: #181c2a;
  --color-contrast-ink: #e4e5e7;
  --color-contrast-line: #454854;
  --color-contrast-accent: #a068f2;
  --overlay-scrim: linear-gradient(180deg, rgba(24, 28, 42, 0.35) 0%, rgba(24, 28, 42, 0.72) 55%, rgba(24, 28, 42, 0.92) 100%);
  --font-heading: "PingFang SC", "HarmonyOS Sans SC", "Microsoft YaHei", "Source Han Sans SC", sans-serif;
  --font-body: "PingFang SC", "HarmonyOS Sans SC", "Microsoft YaHei", "Source Han Sans SC", sans-serif;
  --font-mono: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  --text-xs: 11.4px;
  --text-sm: 14.3px;
  --text-base: 16px;
  --text-lg: 20.0px;
  --text-xl: 25.0px;
  --text-2xl: 31.2px;
  --text-3xl: 39.1px;
  --text-4xl: 48.8px;
  --text-display: clamp(34px, 6.0vw, 77px);
  --text-figure: clamp(28px, 4.3vw, 55px);
  --weight-heading: 716;
  --weight-body: 400;
  --leading-body: 1.76;
  --leading-heading: 1.19;
  --tracking-heading: 0.009em;
  --radius-sm: 1px;
  --radius-md: 2px;
  --radius-lg: 2px;
  --radius-pill: 2px;
  --border-thin: 1px;
  --border-thick: 1px;
  --shadow-1: none;
  --shadow-2: none;
  --space-1: 7px;
  --space-2: 14px;
  --space-3: 21px;
  --space-4: 28px;
  --space-6: 42px;
  --space-8: 56px;
  --container: 1280px;
  --measure: 69ch;
  --gutter: 21px;
  --section-y: 70px;
  --section-y-lg: 98px;
}

:root {
  --rail-w: 200px;
  --bar-h: 58px;
  --grid-cell: calc(var(--space-3) * 2);
}

*, *::before, *::after { box-sizing: border-box; }

html {
  -webkit-text-size-adjust: 100%;
  scroll-behavior: smooth;
}

body {
  margin: 0;
  padding-top: var(--bar-h);
  color: var(--color-ink);
  font-family: var(--font-body);
  font-size: var(--text-base);
  font-weight: var(--weight-body);
  line-height: var(--leading-body);
  background-color: var(--color-surface);
  background-image:
    linear-gradient(to right, color-mix(in srgb, var(--color-line) 60%, transparent) var(--border-thin), transparent var(--border-thin)),
    linear-gradient(to bottom, color-mix(in srgb, var(--color-line) 60%, transparent) var(--border-thin), transparent var(--border-thin));
  background-size: var(--grid-cell) var(--grid-cell);
  -webkit-font-smoothing: antialiased;
}

h1, h2, h3, h4, h5, h6 {
  margin: 0 0 var(--space-2);
  font-family: var(--font-heading);
  font-weight: var(--weight-heading);
  line-height: var(--leading-heading);
  letter-spacing: var(--tracking-heading);
  color: var(--color-ink);
}

h1 { font-size: var(--text-3xl); }
h2 { font-size: var(--text-2xl); }
h3 { font-size: var(--text-xl); }
h4 { font-size: var(--text-lg); }

p { margin: 0 0 var(--space-3); }

a { color: var(--color-primary); text-decoration: none; }
a:hover { color: var(--color-accent); }

ul, ol { margin: 0 0 var(--space-3); padding-left: var(--space-4); }
li { margin-bottom: 6px; }

img { max-width: 100%; height: auto; }

button { font: inherit; color: inherit; }

[hidden] { display: none !important; }

:focus-visible {
  outline: 2px solid var(--color-focus);
  outline-offset: 2px;
}

.mono {
  font-family: var(--font-mono);
  letter-spacing: 0.06em;
}

.wrap {
  width: 100%;
  max-width: var(--container);
  margin-inline: auto;
  padding-inline: var(--space-4);
}

.measure { max-width: var(--measure); }

.rule {
  height: 0;
  border: 0;
  border-top: var(--border-thin) dotted var(--color-line);
  margin-block: var(--space-6);
}

.lede {
  max-width: var(--measure);
  font-size: var(--text-lg);
  line-height: 1.55;
  color: var(--color-ink-soft);
}

/* ---------- skip link ---------- */
.skip-link {
  position: fixed;
  top: var(--space-2);
  left: var(--space-2);
  z-index: 100;
  padding: 8px 14px;
  background: var(--color-accent);
  color: var(--color-accent-ink);
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  text-decoration: none;
  border-radius: var(--radius-sm);
  transform: translateY(-220%);
  transition: transform 0.18s ease;
}
.skip-link:focus {
  transform: none;
  color: var(--color-accent-ink);
}

/* ---------- header / rail ---------- */
.site-header {
  position: fixed;
  inset: 0 auto 0 0;
  z-index: 60;
  width: var(--rail-w);
  display: flex;
  flex-direction: column;
  background: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  border-right: var(--border-thin) dotted var(--color-contrast-line);
}

.site-header::before {
  content: "";
  display: block;
  height: 8px;
  background-image: repeating-linear-gradient(
    to right,
    var(--color-contrast-line) 0 1px,
    transparent 1px 12px
  );
  border-bottom: var(--border-thin) dotted var(--color-contrast-line);
}

.site-header__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-2);
  padding: var(--space-4) var(--space-3);
  border-bottom: var(--border-thin) dotted var(--color-contrast-line);
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  min-width: 0;
  color: var(--color-contrast-ink);
  text-decoration: none;
}
.brand:hover { color: var(--color-contrast-ink); }

.brand__mark {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  flex: none;
  width: 30px;
  height: 30px;
  background: var(--color-primary);
  color: var(--color-primary-ink);
  font-size: var(--text-xs);
  border-radius: var(--radius-sm);
}

.brand__text {
  display: flex;
  flex-direction: column;
  gap: 1px;
  min-width: 0;
}

.brand__name {
  font-family: var(--font-heading);
  font-size: var(--text-lg);
  font-weight: var(--weight-heading);
  letter-spacing: var(--tracking-heading);
  line-height: 1.1;
  color: var(--color-contrast-ink);
}

.brand__line {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  line-height: 1.4;
  color: color-mix(in srgb, var(--color-contrast-ink) 68%, transparent);
}

.site-header__tagline {
  margin: 0;
  padding: var(--space-3);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  line-height: 1.7;
  color: color-mix(in srgb, var(--color-contrast-ink) 62%, transparent);
  border-bottom: var(--border-thin) dotted var(--color-contrast-line);
}

.nav-toggle {
  display: none;
  align-items: center;
  gap: var(--space-1);
  padding: 7px 10px;
  background: transparent;
  border: var(--border-thin) solid color-mix(in srgb, var(--color-contrast-ink) 34%, transparent);
  border-radius: var(--radius-sm);
  color: var(--color-contrast-ink);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.08em;
  cursor: pointer;
}
.nav-toggle:hover { border-color: var(--color-contrast-accent); color: var(--color-contrast-ink); }

.nav-toggle__glyph {
  position: relative;
  width: 14px;
  height: 1px;
  background: currentColor;
  box-shadow: 0 -4px 0 currentColor, 0 4px 0 currentColor;
}

.nav-toggle__text { line-height: 1; }

.site-nav {
  display: flex;
  flex-direction: column;
  flex: 1 1 auto;
  min-height: 0;
  overflow-y: auto;
}

.site-nav__list {
  list-style: none;
  margin: 0;
  padding: var(--space-2) 0;
}
.site-nav__list li { margin: 0; }

.site-nav__link {
  display: flex;
  align-items: baseline;
  gap: var(--space-2);
  padding: var(--space-2) var(--space-3);
  border-left: 2px solid transparent;
  color: color-mix(in srgb, var(--color-contrast-ink) 80%, transparent);
  font-size: var(--text-sm);
  text-decoration: none;
  transition: color 0.18s ease, background-color 0.18s ease, border-color 0.18s ease;
}
.site-nav__link:hover {
  color: var(--color-contrast-ink);
  background: color-mix(in srgb, var(--color-primary) 24%, transparent);
  border-left-color: color-mix(in srgb, var(--color-contrast-accent) 60%, transparent);
}
.site-nav__link[aria-current="page"] {
  color: var(--color-contrast-ink);
  background: color-mix(in srgb, var(--color-primary) 34%, transparent);
  border-left-color: var(--color-contrast-accent);
}

.site-nav__idx {
  flex: none;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  color: var(--color-contrast-accent);
}

.site-nav__label { min-width: 0; }

.site-nav__foot {
  margin-top: auto;
  padding: var(--space-3);
  display: grid;
  gap: var(--space-2);
  border-top: var(--border-thin) dotted var(--color-contrast-line);
}

.site-nav__coord {
  margin: 0;
  font-size: var(--text-xs);
  color: color-mix(in srgb, var(--color-contrast-ink) 52%, transparent);
}

.rail-progress {
  position: absolute;
  top: 0;
  right: 0;
  width: 2px;
  height: 100%;
  background: var(--color-accent);
  transform-origin: top;
  transform: scaleY(var(--progress, 0));
  pointer-events: none;
  transition: transform 0.08s linear;
}

/* ---------- buttons ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-1);
  padding: 10px 16px;
  border: var(--border-thin) solid transparent;
  border-radius: var(--radius-sm);
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  letter-spacing: 0.06em;
  text-decoration: none;
  cursor: pointer;
  transition: background-color 0.18s ease, color 0.18s ease, border-color 0.18s ease;
}

.btn--primary {
  background: var(--color-primary);
  color: var(--color-primary-ink);
}
.btn--primary:hover {
  background: color-mix(in srgb, var(--color-primary) 78%, var(--color-contrast-surface));
  color: var(--color-primary-ink);
}

.btn--ghost {
  background: transparent;
  border-color: color-mix(in srgb, var(--color-contrast-ink) 38%, transparent);
  color: var(--color-contrast-ink);
}
.btn--ghost:hover {
  background: color-mix(in srgb, var(--color-contrast-ink) 12%, transparent);
  color: var(--color-contrast-ink);
}

.btn--block { width: 100%; }

/* ---------- footer ---------- */
.site-footer {
  padding-block: var(--space-8) var(--space-6);
  background: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  border-top: var(--border-thin) dotted var(--color-contrast-line);
}

.site-footer__head {
  display: grid;
  gap: var(--space-2);
  max-width: var(--measure);
}

.site-footer__name {
  margin: 0;
  font-family: var(--font-heading);
  font-size: var(--text-xl);
  font-weight: var(--weight-heading);
  letter-spacing: var(--tracking-heading);
  color: var(--color-contrast-ink);
}

.site-footer__desc {
  margin: 0;
  font-size: var(--text-sm);
  color: color-mix(in srgb, var(--color-contrast-ink) 72%, transparent);
}

.site-footer__band {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-2) var(--space-4);
  margin-top: var(--space-6);
  padding-block: var(--space-3) var(--space-4);
  border-top: var(--border-thin) dotted var(--color-contrast-line);
  border-bottom: var(--border-thin) dotted var(--color-contrast-line);
}

.site-footer__band-link {
  display: inline-flex;
  align-items: baseline;
  gap: 6px;
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  color: color-mix(in srgb, var(--color-contrast-ink) 84%, transparent);
  text-decoration: none;
}
.site-footer__band-link:hover { color: var(--color-contrast-accent); }

.site-footer__band-idx {
  font-size: var(--text-xs);
  color: var(--color-contrast-accent);
}

.site-footer__body {
  display: grid;
  gap: var(--space-6);
  margin-top: var(--space-6);
  grid-template-columns: minmax(0, 1fr);
}

.site-footer__col {
  display: grid;
  gap: var(--space-2);
  align-content: start;
}

.site-footer__title {
  margin: 0;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--color-contrast-accent);
}

.site-footer__list {
  margin: 0;
  padding: 0;
  list-style: none;
  display: grid;
  gap: 6px;
  font-size: var(--text-sm);
  color: color-mix(in srgb, var(--color-contrast-ink) 82%, transparent);
}
.site-footer__list li { margin: 0; }

.site-footer__info {
  margin: 0;
  font-size: var(--text-sm);
  color: color-mix(in srgb, var(--color-contrast-ink) 84%, transparent);
}

.site-footer__note {
  margin: 0;
  font-size: var(--text-xs);
  line-height: 1.7;
  color: color-mix(in srgb, var(--color-contrast-ink) 60%, transparent);
}

.site-footer__legal {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-1) var(--space-3);
  margin: var(--space-6) 0 0;
  padding-top: var(--space-3);
  border-top: var(--border-thin) dotted var(--color-contrast-line);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  color: color-mix(in srgb, var(--color-contrast-ink) 62%, transparent);
}

.site-footer__legal-link {
  color: inherit;
  text-decoration: none;
  border-bottom: var(--border-thin) dotted currentColor;
}
.site-footer__legal-link:hover { color: var(--color-contrast-ink); }

/* ---------- sections & grid ---------- */
.section { padding-block: var(--section-y); }
.section--lg { padding-block: var(--section-y-lg); }

.section--contrast {
  background: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
}
.section--contrast .section__title { color: var(--color-contrast-ink); }
.section--contrast .section__lead { color: color-mix(in srgb, var(--color-contrast-ink) 76%, transparent); }
.section--contrast .section__index { color: var(--color-contrast-accent); }
.section--contrast .lede { color: color-mix(in srgb, var(--color-contrast-ink) 80%, transparent); }

.section__head {
  display: grid;
  gap: var(--space-2);
  margin-bottom: var(--space-6);
}

.section__index {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--color-primary);
}

.section__title {
  margin: 0;
  font-size: var(--text-2xl);
}

.section__lead {
  max-width: var(--measure);
  margin: 0;
  color: var(--color-ink-soft);
}

.grid {
  display: grid;
  grid-template-columns: repeat(12, minmax(0, 1fr));
  gap: var(--gutter);
}

.span-1 { grid-column: span 1; }
.span-2 { grid-column: span 2; }
.span-3 { grid-column: span 3; }
.span-4 { grid-column: span 4; }
.span-5 { grid-column: span 5; }
.span-6 { grid-column: span 6; }
.span-7 { grid-column: span 7; }
.span-8 { grid-column: span 8; }
.span-9 { grid-column: span 9; }
.span-10 { grid-column: span 10; }
.span-11 { grid-column: span 11; }
.span-12 { grid-column: span 12; }

/* ---------- tags ---------- */
.tag {
  display: inline-flex;
  align-items: center;
  gap: 5px;
  padding: 2px 7px;
  border-radius: var(--radius-sm);
  background: var(--color-surface-deep);
  color: var(--color-ink-soft);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.06em;
}

.tag--primary {
  background: var(--color-primary-soft);
  color: var(--color-primary);
}

.tag--accent {
  background: var(--color-highlight);
  color: var(--color-accent);
}

.section--contrast .tag {
  background: color-mix(in srgb, var(--color-contrast-ink) 12%, transparent);
  color: var(--color-contrast-ink);
}
.section--contrast .tag--accent {
  background: color-mix(in srgb, var(--color-accent) 42%, transparent);
  color: var(--color-contrast-ink);
}

/* ---------- figure ---------- */
.figure {
  position: relative;
  overflow: hidden;
  background: var(--color-surface-deep);
  border-radius: var(--radius-md);
}

.figure--fill { aspect-ratio: 16 / 9; }

.figure__img,
.figure img {
  display: block;
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.figure__overlay {
  position: absolute;
  inset: auto 0 0 0;
  padding: var(--space-3);
  background: var(--overlay-scrim);
  color: var(--color-contrast-ink);
  font-size: var(--text-sm);
}

.figure__tag {
  position: absolute;
  top: var(--space-2);
  left: var(--space-2);
}

.figure__caption {
  margin: var(--space-1) 0 0;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  color: var(--color-ink-muted);
}

/* ---------- metric ---------- */
.metric {
  display: grid;
  gap: 6px;
  padding: var(--space-3) 0;
  border-top: var(--border-thin) dotted var(--color-line);
}

.metric__value {
  font-family: var(--font-mono);
  font-size: var(--text-figure);
  font-weight: 500;
  line-height: 1;
  letter-spacing: -0.01em;
  color: var(--color-ink);
}

.metric__label {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--color-ink-soft);
}

.metric__note {
  font-size: var(--text-xs);
  color: var(--color-ink-muted);
}

.section--contrast .metric { border-top-color: var(--color-contrast-line); }
.section--contrast .metric__value { color: var(--color-contrast-ink); }
.section--contrast .metric__label { color: var(--color-contrast-accent); }
.section--contrast .metric__note { color: color-mix(in srgb, var(--color-contrast-ink) 60%, transparent); }

/* ---------- breadcrumbs ---------- */
.breadcrumbs { padding-block: var(--space-3); }

.breadcrumbs__list {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-2);
  margin: 0;
  padding: 0;
  list-style: none;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.06em;
}
.breadcrumbs__list li { margin: 0; }

.breadcrumbs__link {
  color: var(--color-ink-soft);
  text-decoration: none;
}
.breadcrumbs__link:hover { color: var(--color-primary); }

.breadcrumbs__sep { color: var(--color-ink-muted); }

.breadcrumbs__current { color: var(--color-ink); }

/* ---------- filters ---------- */
.filters {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-1);
}

.filter-btn {
  appearance: none;
  padding: 5px 10px;
  background: transparent;
  border: var(--border-thin) dotted var(--color-line);
  border-radius: var(--radius-sm);
  color: var(--color-ink-soft);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.06em;
  cursor: pointer;
  transition: background-color 0.18s ease, color 0.18s ease, border-color 0.18s ease;
}
.filter-btn:hover { border-color: var(--color-primary); color: var(--color-primary); }
.filter-btn[aria-pressed="true"] {
  background: var(--color-accent);
  border-color: var(--color-accent);
  border-style: solid;
  color: var(--color-accent-ink);
}

.section--contrast .filter-btn {
  border-color: var(--color-contrast-line);
  color: color-mix(in srgb, var(--color-contrast-ink) 80%, transparent);
}
.section--contrast .filter-btn[aria-pressed="true"] {
  background: var(--color-contrast-accent);
  border-color: var(--color-contrast-accent);
  color: var(--color-contrast-surface);
}

/* ---------- reveal ---------- */
[data-reveal] {
  opacity: 0;
  transform: translateY(12px);
  transition: opacity 0.32s ease, transform 0.32s ease;
}
[data-reveal].is-visible {
  opacity: 1;
  transform: none;
}

/* ---------- responsive ---------- */
@media (min-width: 1024px) {
  body {
    padding-top: 0;
    padding-left: var(--rail-w);
  }
}

@media (max-width: 1023px) {
  .site-header {
    inset: 0 0 auto 0;
    width: auto;
    height: var(--bar-h);
    flex-direction: row;
    align-items: center;
    justify-content: space-between;
    gap: var(--space-3);
    padding-inline: var(--space-3);
    border-right: 0;
    border-bottom: var(--border-thin) dotted var(--color-contrast-line);
  }

  .site-header::before { display: none; }

  .site-header__inner {
    flex: 1 1 auto;
    padding: 0;
    border-bottom: 0;
  }

  .site-header__tagline { display: none; }

  .nav-toggle { display: inline-flex; }

  .site-nav {
    position: fixed;
    top: var(--bar-h);
    right: 0;
    bottom: 0;
    left: auto;
    z-index: 59;
    width: min(340px, 88vw);
    background: var(--color-contrast-surface);
    border-left: var(--border-thin) dotted var(--color-contrast-line);
    transform: translateX(101%);
    visibility: hidden;
    transition: transform 0.22s ease, visibility 0.22s;
  }

  .site-nav[data-open] {
    transform: none;
    visibility: visible;
  }

  .site-nav__list { padding-top: var(--space-3); }

  .rail-progress {
    top: auto;
    bottom: -1px;
    right: auto;
    left: 0;
    width: 100%;
    height: 2px;
    transform-origin: left;
    transform: scaleX(var(--progress, 0));
  }
}

@media (min-width: 768px) {
  .site-footer__body {
    grid-template-columns: minmax(0, 1.15fr) minmax(0, 1fr);
  }
}

@media (min-width: 1200px) {
  .wrap { padding-inline: var(--space-6); }
}

@media (max-width: 767px) {
  .wrap { padding-inline: var(--space-3); }

  .grid { grid-template-columns: repeat(6, minmax(0, 1fr)); gap: var(--space-3); }

  .span-7, .span-8, .span-9, .span-10, .span-11, .span-12 { grid-column: 1 / -1; }
  .span-4, .span-5, .span-6 { grid-column: span 6; }
  .span-2, .span-3 { grid-column: span 3; }
  .span-1 { grid-column: span 2; }

  .section { padding-block: var(--space-8); }
  .section--lg { padding-block: var(--space-8); }

  .lede { font-size: var(--text-base); }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after {
    animation-duration: 0.001ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.001ms !important;
  }
  [data-reveal] { opacity: 1; transform: none; }
  .rail-progress { transition: none; }
}